Add benchmarks for speedups (#473)

* Add benchmarks for speedups

* Update README.md

* Update README.md

Co-authored-by: Teemu R. <tpr@iki.fi>

* relo

* Update README.md

* document benchmark

* Update README.md

---------

Co-authored-by: Teemu R. <tpr@iki.fi>

devtools/bench/utils/original.py

@@ -0,0 +1,47 @@
+"""Original implementation of the TP-Link Smart Home protocol."""
+import struct
+from typing import Generator
+
+
+class OriginalTPLinkSmartHomeProtocol:
+    """Original implementation of the TP-Link Smart Home protocol."""
+
+    INITIALIZATION_VECTOR = 171
+
+    @staticmethod
+    def _xor_payload(unencrypted: bytes) -> Generator[int, None, None]:
+        key = OriginalTPLinkSmartHomeProtocol.INITIALIZATION_VECTOR
+        for unencryptedbyte in unencrypted:
+            key = key ^ unencryptedbyte
+            yield key
+
+    @staticmethod
+    def encrypt(request: str) -> bytes:
+        """Encrypt a request for a TP-Link Smart Home Device.
+
+        :param request: plaintext request data
+        :return: ciphertext to be send over wire, in bytes
+        """
+        plainbytes = request.encode()
+        return struct.pack(">I", len(plainbytes)) + bytes(
+            OriginalTPLinkSmartHomeProtocol._xor_payload(plainbytes)
+        )
+
+    @staticmethod
+    def _xor_encrypted_payload(ciphertext: bytes) -> Generator[int, None, None]:
+        key = OriginalTPLinkSmartHomeProtocol.INITIALIZATION_VECTOR
+        for cipherbyte in ciphertext:
+            plainbyte = key ^ cipherbyte
+            key = cipherbyte
+            yield plainbyte
+
+    @staticmethod
+    def decrypt(ciphertext: bytes) -> str:
+        """Decrypt a response of a TP-Link Smart Home Device.
+
+        :param ciphertext: encrypted response data
+        :return: plaintext response
+        """
+        return bytes(
+            OriginalTPLinkSmartHomeProtocol._xor_encrypted_payload(ciphertext)
+        ).decode()